This work presents an analysis of a type of concept, the collection, not readily characterized by class inclusion models. Collections, the referent of collective nouns (eg., family, pile, forest, army) are argued to differ from classes in (a) how membership can be determined, (b) part-whole relationships (c) internal structure and (d) the nature of the higher order units they form. From this analysis, it was hypothesized that the psychological integrity of collections is greater than that of classes. Work conducted this past year has found that when the identical stimulus information is presented to subjects (e.g., a picture of trees, or soldiers), organizing the information into collections (forest, army) as opposed to classes (trees, soldiers) affects performance on a number of tasks thought to measure holistic processing: (1) children's ability to make part-whole comparisons and their ability to appreciate the necessity of the quantitative relationships which follow from a part-whole comparison; (2) adult's tendency to make collective vs. distributive inferences; (3) adult's ability to recall numerosity of an array; (4) the ease with which an image is formed of the array. The proposed work will (1) continue to map out the domains in which organization of the same physical input into classes or collections affects cognition, (2) to determine the developmental implications of the work so far only conducted with adults, and (3) to determine more precisely what infomation is differentially encoded or retrived for classes versus collections.